Search Images Maps Play YouTube News Gmail Drive More »
Sign in
Screen reader users: click this link for accessible mode. Accessible mode has the same essential features but works better with your reader.

Patents

  1. Advanced Patent Search
Publication numberUS7177339 B2
Publication typeGrant
Application numberUS 10/637,191
Publication dateFeb 13, 2007
Filing dateAug 8, 2003
Priority dateFeb 8, 2001
Fee statusPaid
Also published asDE10105722A1, DE10105722B4, EP1374356A2, US20040032892, WO2002063733A2, WO2002063733A3
Publication number10637191, 637191, US 7177339 B2, US 7177339B2, US-B2-7177339, US7177339 B2, US7177339B2
InventorsJürgen Müller
Original AssigneeOsram Opto Semiconductors Gmbh
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Semiconductor laser
US 7177339 B2
Abstract
A semiconductor laser has implantation regions that are effective as mode-selective regions in addition to current diaphragms in the edge region of a mesa. As a result, the inner opening of the current diaphragms can be chosen to be larger than in the prior art. This leads to a low ohmic and thermal resistance and enables a high output power.
Images(2)
Previous page
Next page
Claims(12)
1. A semiconductor laser, comprising:
a vertical resonator formed by reflectors;
a photon-emitting active layer disposed between said reflectors;
at least one current diaphragm for laterally circumscribing a current flowing through said photon-emitting active layer; and
mode-selective regions extending in a vertical direction within said vertical resonator and laterally delimiting said vertical resonator, said mode-selective regions being implantation regions extending into said photon-emitting active layer.
2. The semiconductor laser according to claim 1, further comprising a mesa and one of said reflectors is formed in said mesa.
3. The semiconductor laser according to claim 2, wherein said mesa has a diameter of >10 μm.
4. The semiconductor laser according to claim 1, wherein said current diaphragm is formed from an oxide.
5. The semiconductor laser according to claim 1, wherein said current diaphragm defines a current aperture having a given diameter of >3 μm.
6. The semiconductor laser according to claim 5, wherein said current diaphragm has a diameter of >4 μm.
7. The semiconductor laser according to claim 5, wherein said mode-selective regions define an inner opening being larger than said current aperture.
8. The semiconductor laser according to claim 1, wherein said mode-selective regions have an electrical conductivity less than an electrical conductivity of said vertical resonator along a resonator axis.
9. The semiconductor laser according to claim 1, wherein said vertical resonator has an edge area and said mode-selective regions extend in said edge area and a surrounding region of said edge area of said vertical resonator.
10. The semiconductor laser according to claim 1, wherein said current diaphragm is at least two current diaphragms.
11. The semiconductor laser according to claim 1, wherein the semiconductor laser has a multilayer structure and said mode-selective regions are formed within said multilayer structure.
12. A semiconductor laser, comprising:
a substrate;
a vertical resonator formed by reflectors;
a photon-emitting active layer disposed between said reflectors;
at least one current diaphragm for laterally circumscribing a current flowing through said photon-emitting active layer; and
mode-selective regions extending in a vertical direction within said vertical resonator and laterally delimiting said vertical resonator, said mode-selective regions being implantation regions extending into said substrate.
Description
CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of copending International Application No. PCT/DE02/00471, filed Feb. 8, 2002, which designated the United States and was not published in English.

BACKGROUND OF THE INVENTION Field of the Invention

The invention relates to a semiconductor laser having a vertical resonator formed by reflectors, a photon-emitting active layer disposed between the reflectors and a current diaphragm for laterally circumscribing the current flowing through the active layer.

Semiconductor lasers of this type are known as so-called vertical cavity surface-emitting laser (VCSELs). These semiconductor lasers have a layer sequence containing an active layer enclosed between two distributed Bragg reflector (DBR) mirrors. In order to delimit the current injected into the active layer in the lateral direction, provision is made of at least one current diaphragm composed of an oxide in one of the DBR mirrors. The current diaphragms define a current aperture with their inner edge and limit the lateral extent of the pump spot diameter in the active layer.

In principle, monomode operation is also possible with semiconductor lasers of this type. However, this requires a comparatively small pump spot diameter of less than 4 μm, which necessitates a correspondingly small current aperture. However, such small diameters of the current aperture can be produced precisely only with great difficulties. The oxidation is usually affected laterally from the edges of the layer sequence after the layer sequence has been completely deposited. However, this procedure requires accurate knowledge and control of the process parameters.

Moreover, on account of the small current aperture, the known semiconductor lasers with current diaphragms composed of oxide have low optical output powers, high ohmic resistances and high thermal resistances.

SUMMARY OF THE INVENTION

It is accordingly an object of the invention to provide a semiconductor laser that overcomes the above-mentioned disadvantages of the prior art devices of this general type, which is a simple-to-produce monomode semiconductor laser having high optical output power and low ohmic and thermal resistance.

With the foregoing and other objects in view there is provided, in accordance with the invention, a semiconductor laser. The laser contains a vertical resonator formed by reflectors, a photon-emitting active layer disposed between the reflectors, at least one current diaphragm for laterally circumscribing a current flowing through the photon-emitting active layer, and mode-selective regions extending in a vertical direction and laterally delimit the vertical resonator.

The object is achieved according to the invention by virtue of the fact that further mode-selective regions, which extend in the vertical direction and laterally delimit the vertical resonator, are present in addition to the current diaphragm.

The additional mode-selective regions along the axis of the vertical resonator effectively suppress higher modes, since the latter incur higher losses than the fundamental mode in the mode-selective regions. Therefore, only the fundamental mode can reach the laser threshold. At the same time, it is possible to enlarge the current aperture, which, in comparison with the prior art, results in a higher output power and a lower ohmic and thermal resistance.

In a preferred embodiment of the invention, the mode-selective regions are implantation regions with reduced conductivity.

Such implantation regions can also be formed with sufficient precision in a large volume. Moreover, the conductivity can be lowered by use of implantations, thereby attenuating higher-order lateral modes in the implantation regions.

In accordance with an added feature of the invention, a mesa is provided and one of the reflectors is formed in the mesa. The mesa has a diameter of >10 μm.

In accordance with another feature of the invention, the current diaphragm is formed from an oxide.

In accordance with an additional feature of the invention, the current diaphragm defines a current aperture having a given diameter of >3 μm. Additionally, the current diaphragm has a diameter of >4 μm.

In accordance with a further feature of the invention, the mode-selective regions define an inner opening being larger than the current aperture. The mode-selective regions have a conductivity being less than a conductivity of the vertical resonator along a resonator axis. Preferably; the mode-selective regions are implantation regions. The vertical resonator has an edge area and the mode-selective regions extend in the edge area and a surrounding region of the edge area of the vertical resonator.

In accordance with another added feature of the invention, the current diaphragm is at least two current diaphragms.

In accordance with a concomitant feature of the invention, the semiconductor laser has a multilayer structure and the mode-selective regions are formed in the multilayer structure.

Other features which are considered as characteristic for the invention are set forth in the appended claims.

Although the invention is illustrated and described herein as embodied in a semiconductor laser, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.

The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING

The single FIGURE of the drawing is a cross-sectional view through a semiconductor laser according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the single FIGURE of the drawing in detail, there is shown a semiconductor laser 1 having a lower Bragg reflector 3 applied to a substrate 2, a cavity 4 with a photon-emitting active zone being formed on the reflector 3. Situated above the cavity 4 is an upper Bragg reflector 5, in which current diaphragms 6 are formed. An inner edge of the current diaphragms 6 defines current apertures 7 delimiting the lateral extent of the currents injected into the cavity 4. As a result, a photon-emitting pump spot 8 is produced in the cavity 4, which pump spot 8 optically amplifies the radiation reflected between the lower Bragg reflector 3 and the upper Bragg reflector 5. Part of the radiation is allowed to pass by the upper Bragg reflector 5 and can leave the semiconductor laser 1 through an exit opening 9 in an annular front side contact 10. A rear side contact 11 is additionally present on a rear side of the substrate 2.

Generally, the upper Bragg reflector 5 is configured as a mesa 12. Situated in edge regions of the mesa 12 are implantation regions as mode-selective regions 13, which also extend into the substrate 2. The mode-selective regions 13 have an inner opening 14. The cross-sectional area of the inner opening 14 is always larger than the area of the current apertures 7.

By implantation, the conductivity of the material in the mode-selective regions 13 is less than the conductivity in the inner opening 14 of the mode-selective regions 13. Higher-order modes that extend into the mode-selective regions 13 are therefore attenuated. An optical amplification takes place only in the region of the inner opening 14, that is to say in the region of the fundamental mode. Therefore, the diameter of the current apertures 7 can be chosen to be larger than in the prior art.

The larger opening of the current apertures 7 in comparison with the prior art leads to a lower series resistance of the semiconductor laser 1, and to a lower thermal resistance, which results in weaker ageing effects. Moreover, the large current apertures 7 lead to a large pump spot 8 and thus to higher optical output powers. The inner diameter of the current apertures 7 is more than 3 μm, preferably more than 4 μm, in the semiconductor laser 1.

What is also particularly advantageous is that the production of the current diaphragms 6 can be controlled better in comparison with the prior art, since the production-dictated deviations during the production of the current diaphragms 6 are smaller as seen in relative terms.

The double embodiment of the current diaphragms 6 furthermore makes it possible to avoid excessive edge elevations of the current injection into the cavity 4 which intrinsically also jeopardize the monomode nature.

The invention described here is not restricted to specific materials. The known materials that can be used for the type of semiconductor lasers 1 described can be considered. The customary methods known to the person skilled in the art are suitable for production.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US5245622 *May 7, 1992Sep 14, 1993Bandgap Technology CorporationVertical-cavity surface-emitting lasers with intra-cavity structures
US5256596 *Mar 26, 1992Oct 26, 1993Motorola, Inc.Top emitting VCSEL with implant
US5258316 *Mar 26, 1992Nov 2, 1993Motorola, Inc.Etching
US5446752 *Jul 7, 1994Aug 29, 1995MotorolaVCSEL with current blocking layer offset
US5493577 *Dec 21, 1994Feb 20, 1996Sandia CorporationEfficient semiconductor light-emitting device and method
US5557627 *May 19, 1995Sep 17, 1996Sandia CorporationVisible-wavelength semiconductor lasers and arrays
US5719891 *Dec 18, 1995Feb 17, 1998Picolight IncorporatedConductive element with lateral oxidation barrier
US5729566 *Jun 7, 1996Mar 17, 1998Picolight IncorporatedLight emitting device having an electrical contact through a layer containing oxidized material
US5812577 *Nov 13, 1995Sep 22, 1998Sharp Kabushiki KaishaSurface-emitting laser
US5822356Feb 6, 1997Oct 13, 1998Picolight IncorporatedLens layers oxidized in regions adjacent to nonoxidized regions; semiconductors, reduced reflection, scattering
US5881085Jul 25, 1996Mar 9, 1999Picolight, IncorporatedAluminum-containing oxide-formed intracavity lens in which optical aberrations and scattering are reduced
US5893722 *Apr 28, 1997Apr 13, 1999Honeywell Inc.Fabrication of vertical cavity surface emitting laser with current confinement
US5903590 *May 20, 1996May 11, 1999Sandia CorporationVertical-cavity surface-emitting laser device
US6064683 *Dec 12, 1997May 16, 2000Honeywell Inc.Bandgap isolated light emitter
US6144682Oct 29, 1998Nov 7, 2000Xerox CorporationSpatial absorptive and phase shift filter layer to reduce modal reflectivity for higher order modes in a vertical cavity surface emitting laser
US6185241 *Oct 29, 1998Feb 6, 2001Xerox CorporationMetal spatial filter to enhance model reflectivity in a vertical cavity surface emitting laser
US6208007 *Jul 28, 1999Mar 27, 2001The Regents Of The University Of CaliforniaBuried layer in a semiconductor formed by bonding
US6534331 *Jul 24, 2001Mar 18, 2003Luxnet CorporationMethod for making a vertical-cavity surface emitting laser with improved current confinement
US6542527 *Aug 23, 1999Apr 1, 2003Regents Of The University Of MinnesotaVertical cavity surface emitting laser
US6618414 *Mar 25, 2002Sep 9, 2003Optical Communication Products, Inc.Hybrid vertical cavity laser with buried interface
US6680963 *Jul 24, 2001Jan 20, 2004Lux Net CorporationVertical-cavity surface emitting laser utilizing a reversed biased diode for improved current confinement
US6751245 *Jun 2, 2000Jun 15, 2004Optical Communication Products, Inc.Single mode vertical cavity surface emitting laser
US6882673 *Jan 15, 2002Apr 19, 2005Optical Communication Products, Inc.Mirror structure for reducing the effect of feedback on a VCSEL
US6904072 *Dec 28, 2001Jun 7, 2005Finisar CorporationVertical cavity surface emitting laser having a gain guide aperture interior to an oxide confinement layer
Non-Patent Citations
Reference
1Michalzik, R. et al.: "High-Bit-Rate Data Transmission with Short-Wavelength Oxidized VCSEL's: Toward Bias-Free Operation", IEEE Journal of Selected Topics in Quantum Electronics, vol. 3, No. 2, Apr. 1997, pp. 396-404.
2Morgan, R. A. et al.: "Hybrid Dielectric/AIGaAs Mirror Spatially Filtered Vertical Cavity Top-Surface Emitting Laser", American Institute of Physics, Applied Physics Letters, vol. 66, No. 10, Mar. 6, 1995, pp. 1157-1159.
3Nishiyama, N. et al.: "Multi-Oxide Layer Structure for Single-Mode Operation in Vertical-Cavity Surface-Emitting Lasers", IEEE Photonics Technology Letters, vol. 12, No. 6, Jun. 2000, pp. 606-609.
4Wu, Y. A. et al.: "High-Yield Processing and Single-Mode Operation of Passive Antiguide Region Vertical-Cavity Lasers", IEEE Journal of Selected Topics in Quantum Electronics, vol. 3, No. 2, Apr. 1997, pp. 429-434.
5Zhou, D. et al.: "Simplified-Antiresonant Reflecting Optical Waveguide-Type Vertical-Cavity Surface-Emitting Lasers", American Institute of Physics, Applied Physics Letters, vol. 76, No. 13, Mar. 27, 2000, pp. 1659-1661.
Classifications
U.S. Classification372/98, 372/46.015, 372/43.01
International ClassificationH01S3/08, H01S5/20, H01S5/183, H01S5/00
Cooperative ClassificationH01S2301/18, H01S5/18311, H01S5/2059, H01S5/18333, H01S5/18308
European ClassificationH01S5/183C7M2
Legal Events
DateCodeEventDescription
Jul 12, 2010FPAYFee payment
Year of fee payment: 4
Feb 14, 2005ASAssignment
Owner name: OSRAM OPTO SEMICONDUCTORS GMBH, GERMANY
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:MULLER, JURGEN;REEL/FRAME:016252/0775
Effective date: 20030825